The biggest problem I have with this game is that the Lions host the Bears at the same time the Brewers host the Cardinals. I'll be flipping back and forth all night.
For the Lions, the biggest point is that this is the first Monday night game in Detroit in 10 years and Kevin Seifert said that the place was already a zoo by mid-afternoon. For added adrenaline, the Tigers are playing in Texas this afternoon. They'll want to keep pace with the Packers in the NFC North, and they'll want to prove they can beat the defending division champ.
For the Bears, they really need to win this game. If they lose tonight, they'll have three losses on the season and be three back from the division lead. Also, it'll be their second divisional loss of the season, and they went 5-1 against the NFC North last season. They have a favorable schedule the rest of the way, but a loss will probably leave them playing for a wild card.